Correct statements from the following are:
A. Potassium dichromate is an oxidising agent and it oxidises FeSO₄ to Fe₂(SO₄)₃ in acidic medium.
B. Sodium dichromate can be used as primary standard in volumetric estimation.
C. CrO₄²⁻ and Cr₂O₇²⁻ are interconvertible in aqueous solution by varying the pH of the solution.
D. Cr-O-Cr bond angle in Cr₂O₇²⁻ is 126°.
Choose the correct answer: